Mark Zuckerberg was on hostile turf as spoke to executives at the world's biggest annual gathering of the mobile industry, renewing attempts to win their backing to help reach billions of users with no Internet access.

U.S. spy chief James Clapper said that when he made a secret visit to North Korea in November to bring home two jailed Americans he was first given a 12-course banquet and then told that his security could not be guaranteed.

Iran must commit to a verifiable freeze of at least 10 years on sensitive nuclear activity for a landmark deal to be reached, but the odds are still against sealing an agreement, Obama told Reuters, an exclusive report says.